Predicting STOP-Sign Compliance at All-Way Stop Intersections in Close Proximity to Signalized Intersections Stephen A. Arhin Ph.D., P.E., PTOE, PMP a* a Howard University Transportation Research Center 2300 Sixth Street, NW, Washington, DC 20059 Adam Gatiba b b Howard University Transportation Research Center 2300 Sixth Street, NW, Washington, DC 20059 Melissa Anderson c c Howard University Transportation Research Center 2300 Sixth Street, NW, Washington, DC 20059 Melkamsew Ribbisso d d Howard University Transportation Research Center 2300 Sixth Street, NW, Washington, DC 20059 Abstract:- STOP-signs (at unsignalized intersections) that are in close proximity to signalized intersections are often violated by drivers while “speeding up” to go through the upstream or downstream signalized intersection that have the green interval upon approach. It is thought that if the distance between the upstream or downstream signalized and the AWSC intersection is long, drivers usually comply with the STOP signs at the AWSC intersection. This research determined driver compliance rates (CRs) at All-Way STOP Control (AWSC) intersections that are in close proximity to upstream or downstream signalized intersections and, explored the existence of a relationship between CR and the distance between a pair of signalized and AWSC intersections. Thirty (30) isolated segments with combinations of signalized and AWSC intersections in the District of Columbia were selected for the study. Field data (traffic volumes) were obtained at each intersection in addition to observation of driver compliance with STOP signs at AWSC intersections via video playback. In all, 13,956 observations were made at 57 AWSC intersections in 2017. The study showed that lower CRs were observed at AWSC intersections that are in closer proximity to the signalized intersections. Thus, the shorter the distance from the existing AWSC to signalized intersections, the lower the CR (or higher violation rate). Based on the data obtained, a non-linear relationship between CR and distance between pairs of intersections was developed. From the model, to achieve a minimum compliance rate of 95% at an AWSC, an optimal distance of approximately 1,300 feet between the intersections is required. Keywords: Compliance Rate, All-Way STOP Controls, Signalization 1. INTRODUCTION Most intersections in urban areas are either signalized or unsignalized (STOP or YIELD-Controlled). As a result road segments in such areas have a combination of both types of intersections. In order to ensure safety of drivers and pedestrians, it important for drivers to comply with traffic control devices. While compliance with traffic signals is relatively high, compliance with STOP signs is relatively low, especially for unsignalized intersections that are close to those signalized. Drivers often violate STOP signs in order to travel through the next signalized intersection that may have the green interval on approach. This research explores the existence of a relationship between STOP sign compliance rate and the distance between an AWSC and a signalized intersection (downstream or upstream). Thirty segments with combinations of signalized and AWSC intersections in an urban area (Washington DC) were selected for this study. Each segment consisted of at least two signalized and one AWSC intersections. STOP sign compliance was observed via video playback during the off-peak period (10:00AM to 1:00PM) based on which the compliance rate (CR) at each AWSC intersection was then computed. A model was then developed to predict CR based on the distance between AWSC and upstream or downstream signalized intersections. 2. LITERATURE REVIEW Traffic flow interruptions are most likely to originate at or near intersections. Ideally, it is recommended that the minimum spacing for intersections in urban areas is 0.5 miles [1]. However, in some urban areas, intersections are much more closely spaced since there are often competing needs for providing land access. When access to an intersection is regulated by traffic signals or regulatory signs, it said to be controlled, while it is uncontrolled when access is regulated by the right-of-way rules. Controlled intersections are either signalized or unsignalized. Signalized intersections are controlled by traffic lights while unsignalized intersections are controlled by either STOP signs or yield signs. The STOP signs are installed either on the minor-roads only (Two-Way STOP control-TWSC) or on all approaches (All-Way STOP control-AWSC). Roadway networks in dense urban areas consist of combinations of signalized and unsignalized intersections which may affect throughput and may have safety implications. The Federal Highway Administration (FHWA) reported that since 2005, there has been a decline in the overall number of crashes that occur at or in close proximity to intersections [2]. Nevertheless, crashes at intersections are still a major concern for traffic authorities. In 2015, a total of 48,923 vehicles were involved in fatal crashes in the United States. Out of the total, approximately 4.4% (2,157) of the fatal crashes occurred at STOP- International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 http://www.ijert.org IJERTV8IS070231 (This work is licensed under a Creative Commons Attribution 4.0 International License.) Published by : www.ijert.org Vol. 8 Issue 07, July-2019 1021